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mpi_hello.c

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+/* File:       
+ *    mpi_hello.c
+ *
+ * Purpose:    
+ *    A "hello,world" program that uses MPI
+ *
+ * Compile:    
+ *    mpicc -g -Wall -std=C99 -o mpi_hello mpi_hello.c
+ * Usage:        
+ *    mpiexec -n<number of processes> ./mpi_hello
+ *
+ * Input:      
+ *    None
+ * Output:     
+ *    A greeting from each process
+ *
+ * Algorithm:  
+ *    Each process sends a message to process 0, which prints 
+ *    the messages it has received, as well as its own message.
+ *
+ * IPP2  Section 3.1 (pp. 90 and ff.)
+ */
+#include <stdio.h>
+#include <string.h>  /* For strlen             */
+#include <mpi.h>     /* For MPI functions, etc */ 
+
+const int MAX_STRING = 100;
+
+int main(void) {
+   char       greeting[MAX_STRING];  /* String storing message */
+   int        comm_sz;               /* Number of processes    */
+   int        my_rank;               /* My process rank        */
+
+   /* Start up MPI */
+   /* 第1处代码补全开始 */
+   
+   /* 第1处代码补全结束 */ 
+
+   /* Get the number of processes */
+   /* 第2处代码补全开始 */
+   
+   /* 第2处代码补全结束 */ 
+
+   /* Get my rank among all the processes */
+   /* 第3处代码补全开始 */
+   
+   /* 第3处代码补全结束 */ 
+
+   if (my_rank != 0) { 
+      /* Create message */
+      sprintf(greeting, "Greetings from process %d of %d!", 
+            my_rank, comm_sz);
+      /* Send message to process 0 */
+      /* 第4处代码补全开始 */
+      
+      /* 第4处代码补全结束 */ 
+   } else {  
+      /* Print my message */
+      printf("Greetings from process %d of %d!\n", my_rank, comm_sz);
+      for (int q = 1; q < comm_sz; q++) {
+         /* Receive message from process q */
+         /* 第5处代码补全开始 */
+   
+         /* 第5处代码补全结束 */
+         /* Print message from process q */
+         printf("%s\n", greeting);
+      } 
+   }
+
+   /* Shut down MPI */
+   /* 第6处代码补全开始 */
+   
+   /* 第6处代码补全结束 */ 
+
+   return 0;
+}  /* main */